1. Field of the Invention
The present invention concerns a multifunctional rotary cutting head. It is more specifically intended for equipping portable cutting tools such as edge-trimmers, also called grass cutters or grass trimmers, brush cutters, motorized grass mowers, grass-trimmers or the like.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Generally, it is customary to classify under the name of edge-cutter or grass-cutter all devices whose function it is to cut lawns or grasses with low resistance. The cutting heads used for this purpose are generally of the type where the cutting elements are constituted by lengths of flexible wires of plastic material, for example of ‘Nylon’ yarn. On the other hand, the devices that are used for cutting vegetation already lignified (small brush, tree or shrub shoots, tall grasses, hedges, . . . ) are more often called brush-cutters, hedge-trimmers, and their cutting head uses rotary metallic or hard plastic blades. By the way of examples documents US-2001/0023542, U.S. Pat. No. 6,401,344, U.S. Pat. No. 6,944,956, WO-2004/064489, WO-2005/032237, WO-2006/017372, WO-2008/139246, FR-2888085 are cited which describe various possible layouts of cutting heads using cutting elements constituted by lengths of flexible cutting wires. Examples of cutting heads using metallic cutting wires are for instance described in document WO-2007/099443.
These cutting heads are mounted at the distal end of a handle equipped with a U-shaped grip or a dual guide and control handle for the motor ensuring the rotational drive of said cutting heads, as well as with a ring for fastening a carrying harness.
The portable cutting devices currently available on the market are either designed for use of only one type of cutting tool, or, for the sake of being multifunctional, certain machines provide for each of these types of elements a specific interchangeable head: one for wire, one for a metal blade, etc.
If one wants to go from one type to the other, it is necessary to remove all or a portion of the support of the one to replace it by all or part of the support of the other. These two types of support require a removal and the use of one or several tools. This situation has additional disadvantages:                The need for training the user in the removal (often left-hand thread)/disassembly and re-assembly of the cutting tool supports, requiring the use of cutting tools one always has to keep within reach.        Loss of time and risk of injury; loss of parts during removal and re-assembly.        
It happens frequently that because of the location of the surfaces on which shearing or brush clearing needs to be performed, the users need to acquire one wire device for cutting soft grasses (for example, surfaces around trees or near hard obstacles such as edges of walls, terraces or bodies of masonry, etc.) and a blade device for the clearing of brush in high and bard grasses, or in ligneous plantings (brambles, ferns, . . . ) or in brush, or for the cutting of hedges or the thinning out of shrubby trees. It is clear that such a situation results in increased expenses for acquisition and initiation of the cutting materials.
To remedy the disadvantages of the devices of the aforementioned kind which are meant for specific cutting jobs, in document WO-2007/099443, a tool iota shrub slasher with dual action has been proposed for combined cutting of grass and brush this tool consisting of a rectangular blade with a center hole for connection to a rotary head of a landscape brush rake and of suitable materials which are provided with a pair of cylindrical through-holes for the insertion of small lengths of Nylon or another durable plastic material. This tool allows simultaneous cutting of grass and brush, while avoiding the operations of attaching and detaching the blade, while also achieving efficient disintegration of the grass and brush.
This tool is not versatile in so far as, even if it allows simultaneous cutting of grass and small woody plants in order to proceed with the fragmentation of the cut materials, it is not suitable for mounting on an edge-trimmer or grass cutter that has to be used in proximity to bard obstacles.